Device setting modifications for 3D flatpanel imaging in skull base surgery

Comparison of 3D C-arm-based registration to conventional pair-point registration regarding navigation accuracy in ENT surgery

OBJECTIVE

Navigation surgery on the skull base requires high navigation accuracy. The registration process is related to the main loss in accuracy. This study compared titanium screw registration with an inbuilt registration process of a 3-dimensional (3D) C-arm.

STUDY DESIGN

Experimental phantom study.

SETTING

Operating room.

SUBJECTS AND METHODS

Four skull models were fabricated with a 3D printer based on the patient's computed tomography (CT) data sets and fitted with an individually customized silicone skin. A 3D-isocentric C-arm fluoroscopic image intensifier system combined with a flat panel detector performed scans of petrous bones (PB) and paranasal sinuses (PS). The navigation accuracy of pair-point registration (PPR) with titanium screws was compared with C-arm-based registration.

RESULTS

Overall navigation accuracy was 1.53 ± 0.51 mm after PPR and 1.26 ± 0.12 mm after C-arm registration (P = .0259). PPR showed the best accuracy results on PS (1.28 ± 0.69 mm), followed by right PB (1.43 ± 0.52 mm) and left PB (1.74 ± 0.69 mm). A significant difference was seen only between PS and left PB (P = .0206). In contrast, C-arm registration revealed significantly lower target registration errors (TREs) on PB (0.99 ± 0.23 mm right PB, P < .0001; 1.2 ± 0.35 mm left PB, P = .0412) compared with PS. When comparing both registration modalities, C-arm registration was significantly superior on PB. With respect to specific anatomic locations, C-arm-based registration showed significantly lower TREs on the frontal and lateral skull base than PPR.

CONCLUSION

C-arm-based navigation shows higher navigation accuracy on the skull base compared with PPR. As the 3D C-arm allows real-time imaging and real-time navigation, it will be a helpful tool for skull base surgeons.

Pediatric radiology in oto-rhino-laryngology

Head and neck diseases in children and adolescents present special diagnostic and differential diagnostic challenges to ENT surgeons as well as to radiologists. Both disciplines have to adapt the latest radiological and interventional technologies to the needs of the pediatric patient in order to enable a minimally invasive but successful diagnostic procedure. High quality sonography by an experienced examiner is often the only imaging technique that is necessary in children and adolescents. Radiographs are rarely indicated in pediatric head and neck diseases. MRI, compared to computed tomography, has the advantage of absent radiation exposure. Additionally, due to current advances in high resolution techniques to delineate very small details or in visualization of different tissue characteristics, it has become an integral part of pre- and postoperative imaging. However, children should not be denied an adequate diagnostic procedure even if it includes sedation, intervention, or exposure to radiation. The responsible use of the diagnostic options under consideration of the therapeutic consequences is essential. It is most likely to be successful in a close interdisciplinary cooperation of pediatric ENT specialists and radiologists as well as pediatric anesthesiologists in selected cases. Although benign diseases predominate in children and adolescents, the possibility of malignancy has to be considered in cases of atypical clinical and radiological findings. In many of these young patients, the outcome and the probability of survival are directly associated with the initial diagnostic and therapeutic strategies, which should therefore be in accordance with the current guidelines of pediatric oncology therapy studies. Our collection of clinical cases consists of representative examples of useful diagnostic approaches in common and age specific diagnoses as well as in rare diseases and malformations. It shows the significance of a special knowledge in embryology and normal postnatal development for the differentiation of normal variants from pathological findings. Only in considering the results of imaging studies in their clinical context, it is possible to succeed in detecting a syndrome behind a single malformation or adequately caring for patients with a chronic disease such as cystic fibrosis.